EP3764056A1 - Chromatic confocal measuring device - Google Patents

Abstract

A chromatic confocal measuring device for measuring distances and / or thicknesses of several points has a light source (1), which emits polychromatic measuring light (2) through a light exit surface, and at least one first confocal aperture (3, 10) through which the measuring light (2) and which comprises a plurality of point-shaped openings or at least one slot-shaped opening. The measuring device also includes imaging optics (4, 5) which are set up to cause a chromatic focus shift of the measuring light and to image the first confocal aperture (3) in a measuring volume, with different wavelengths being focused at different heights. A first receiving and evaluation unit (8) is designed to measure the intensity of the measurement light reflected from the measurement object as a function of the wavelength and the transverse position of the reflection point on the measurement object and to measure distances and / or thicknesses from several points or one into at least one To determine the spatial direction of the extended area of the measurement object (6). According to the invention, the light source (1) is a laser-pumped luminophore-based light source and the exit surface is elongated.

Description

BACKGROUND OF THE INVENTION 1. Field of the invention

The invention relates to a chromatic-confocal measuring device for the simultaneous measurement of distances and / or thicknesses from several points or an area of a measurement object that is extended in at least one spatial direction. The measuring device comprises a light source which emits polychromatic measuring light through a light exit surface, and at least one first confocal aperture through which the measuring light passes. The first confocal aperture comprises a plurality of point-shaped openings or at least one slot-shaped opening. The measuring device also includes imaging optics which are set up to cause a chromatic focus shift of the measuring light and to image the first confocal aperture in a measuring volume, with different wavelengths being focused at different heights, as well as a first receiving and evaluation unit which is designed to to measure the intensity of the measurement light reflected by the measurement object as a function of the wavelength and the transverse position of the reflection point on the measurement object and to determine distances and / or thicknesses from several points or an area of the measurement object that extends in at least one spatial direction.

2. Description of the prior art

From the WO 2016/092348 A1 A chromatic-confocal height measuring device is known which has a plurality of measuring points arranged in a line in order to enlarge the measuring volume transversely to the optical axis.

In the DE 10 2018 114 860 A1 a chromatic confocal measuring device is also described which comprises slit diaphragms as confocal diaphragms, so that a continuous, extensive area of the measurement object can be measured along the projection of the diaphragm.

Known measuring devices have the disadvantage that either light from a point light source has to be distributed over the entire measurement volume, which leads to a low intensity and thus a limitation of the possible measuring rate, or a large number of point light sources must be used, which leads to high costs. Known light sources have too little output power to operate a chromatic-confocal line detector at a high frequency.

SUMMARY OF THE INVENTION

It is therefore the object of the invention to provide an inexpensive light source which is suitable for operating a chromatic-confocal line detector at a high frequency.

This object is achieved by providing a luminophore-based light source, the light exit surface of which is elongated.

A luminophore-based light source is understood to mean a light source in which a luminescent material (luminophore) is excited by means of a pump source (typically laser or LED) and emits light through a physical process, in particular phosphorescence, fluorescence or scintillation. A luminophore is here generally a radiation-converting substance.

An elongated exit surface means that the surface is significantly longer in one spatial direction than in the other, in particular by at least one order of magnitude.

Luminophore-based light sources are known per se, but none that would be suitable for this application.

According to the invention, a measuring device of the type mentioned above is provided, the light source of which is a laser-pumped luminophore-based light source and the exit surface of the light source is elongated. This has the advantage that the light source can illuminate the entire confocal aperture and at the same time has a high efficiency and a high light yield.

The first confocal aperture comprises a plurality of point-shaped openings or at least one slot-shaped opening. In particular, the punctiform openings arranged in a row, preferably at regular intervals. In the case of punctiform openings, a so-called multipoint sensor is involved, which is set up to measure a series of points on the measurement object. In this case, the first confocal aperture can also be designed as ends of a row of fibers, each fiber end corresponding to a point-like opening. If the first confocal aperture comprises a slit-shaped opening, it is a so-called chromatic line sensor which is set up to illuminate and measure a linear area on the measurement object. The density of the measuring points in the linear area depends on the receiving and evaluation unit and its transversal resolution.

The first receiving and evaluation unit preferably comprises a spectrometer which detects the intensities of received light as a function of the wavelength.

According to a preferred embodiment of the invention, the light source comprises at least one pump source which emits pump light and directs it onto a luminophore which converts the pump light into polychromatic light. As a rule, the pump light is almost monochromatic. Laser diodes are preferably used as pump sources because of the high intensity that can be achieved.

The pump light can also be converted into polychromatic light by a plurality of luminophores which are arranged separately from one another.

In some exemplary embodiments, the polychromatic light then passes through a homogenizer in such a way that the intensity of the light emerging from the exit surface is at least almost uniformly distributed. The homogenizer is preferably designed as a thin plate, preferably made of glass, through which the light essentially propagates in a first spatial direction, while the plate functions as an optical waveguide in a second spatial direction, and the light propagates in the third spatial direction and thus evenly can distribute. This has the purpose of uniform illumination over the measurement volume. The luminophores can be approximately punctiform here or have a small volume.

The homogenizer can, for example, have a section which has the shape of a preferably square truncated pyramid which is arranged such that the polychromatic light enters the section via the top surface of the truncated pyramid. It has surprisingly been shown that the pyramidal shape leads to a particularly uniform distribution of intensity on the base of the truncated pyramid. In the case of rotationally symmetrical homogenizers, an undesirable concentration of the polychromatic light on the axis of symmetry is usually observed.

A pyramidal homogenizer is also advantageous if a shaping device to be explained is used which makes the cross section of the light distribution more elongated and into which the polychromatic light has to be coupled. For example, if the conversion device contains optical fibers, the polychromatic light can only enter the fibers at small angles. The shape of the truncated pyramid minimizes the amount of light that hits the fibers at too steep an angle.

Side surfaces of the truncated pyramid can be inclined in such a way that polychromatic light guided in the section is guided by total reflection in the homogenizer. This eliminates the need for mirroring the side surfaces.

A homogenizer of the type described can also be combined with all of the following embodiments.

According to a preferred embodiment of the invention, the luminophore is rod-shaped. Light emerging through a side face of the rod-shaped luminophore is advantageously used as measuring light. The side surface is a surface that extends over the length of the rod. This has the advantage that only one pump source and only one luminophore are required to emit light over an elongated area, the light being emitted from a continuous area instead of from several point sources.

The rod-shaped luminophore can have a base (and cross-section) of any shape, for example circular or polygon. The base is the area on one End of the rod. The geometric shape is therefore preferably a cylinder or a prism, the height of which is significantly greater than the diameter of the base area.

The light preferably enters through one of the base surfaces of the rod-shaped luminophore. Another advantageous possibility is to pump from both base surfaces of the rod-shaped luminophore, which improves the light yield and makes the radiation at least partially more uniform over the length of the rod.

Alternatively, pump light enters through a side surface of the luminophore. In this case, either several pump sources are used over the length of the rod-shaped luminophore, or pump light from a single pump source is focused on a line segment at the location of the luminophore, for example by means of focusing optics with a cylindrical lens.

The rod-shaped luminophore is advantageously designed such that it acts as an optical waveguide for the pump light and / or the measurement light. This is achieved primarily through the choice of surface properties (smooth surface) and a small diameter (typically approx. 5 µm or approx. 50 µm, depending on the type of optical waveguide required).

LED luminophores usually have mean path lengths in the range 0.2mm to 0.5mm for absorption and frequency-shifted light emission. In the case of approximately point-shaped light sources, the pump light must be held in place by multiple light scattering at grain boundaries in a small luminous area below 100 µm in order to obtain a light spot that is small enough for the point-shaped distance measurement. With the rod-shaped luminophore, the pump light can be guided linearly and without scattering, like in a single or multimode fiber (optical waveguide).

According to a particularly preferred embodiment of the invention, the light source comprises a slit diaphragm, the slit of the slit diaphragm being the light exit surface of the light source. The slot can simultaneously serve as the first confocal aperture of the measuring device. The aperture advantageously shields light that is not directed through the exit surface in order not to influence the measurement.

According to a particularly preferred embodiment of the invention, the slit diaphragm is tilted relative to the longitudinal axis of the rod-shaped luminophore. This has the advantage that an uneven emission of light over the length of the luminophore can be at least partially compensated for, since a percentage of more light passes through the part of the slit diaphragm which is closer to the luminophore than through the part further away. The slit diaphragm is therefore advantageously tilted so that it is closer to an area of the luminophore which emits less light and further away from an area of the luminophore which emits more light.

According to a particularly preferred embodiment of the invention, that of an entry surface through which the pump light enters the luminophore, the opposite end face of the rod-shaped luminophore is made reflective. This has the effect that pump light which completely passes through the luminophore is reflected at the end and passes through the luminophore again. This results in a higher yield and more uniform radiation.

According to a particularly preferred embodiment of the invention, the luminophore is designed to be conical, in particular as a truncated cone or a cone. This results in a more even light output. The entry surface is preferably the larger base area of the truncated cone or through the base area of the cone. The conical luminophore is advantageously designed in such a way that it acts as an optical waveguide for the pump light. As a result, the pump light is concentrated in the narrower part of the cone / truncated cone, which leads to a higher yield per unit volume.

According to a particularly preferred embodiment of the invention, the light source comprises a parabolic mirror. This focuses light that does not leave the luminophore in the direction of the exit surface of the light source, at least partially in the direction of the exit surface and thus allows a higher yield.

According to a particularly preferred embodiment of the invention, part of the outer surfaces (part of the side surface / side surfaces and / or at least one base surface) of the rod-shaped luminophore is mirrored, the desired exit surface not being mirrored is. This brings about a higher light yield, since radiation which is not emitted in the direction of the light exit surface is at least partially reflected in the direction of the light exit surface.

The luminophore advantageously consists of a mixture of different luminophore substances which emit light of different wavelengths. This leads to a broader polychromatic spectrum. There is sometimes an effect of secondary luminescence when light of a first emission wavelength excites another luminophoric substance which emits light of a longer emission wavelength.

A homogeneous mixture of the various luminophoric substances is preferably used.

The mixing ratio of the various luminophore substances is preferably changed over the length and / or over the radius of the rod-shaped luminophore. In this way, effects of the secondary emission can be used or offset. A layer structure with pure layers of different substances is also possible.

The luminophore advantageously consists either of a single crystal or of pressed powder.

According to a preferred embodiment of the invention, the measuring device comprises a second receiving and evaluation unit which is designed to detect an image of the measurement object. This is designed in particular as a so-called chromatic camera, which uses the different focus positions of the different wavelengths on the object in order to generate an image with an improved depth of field.

According to a preferred embodiment of the invention, the measuring device comprises a second imaging optics, which are spatially separated from the first imaging optics, the first imaging optics and the second imaging optics each comprising an additional optical element, which a chromatic focus shift transversely to the optical axis of the respective imaging optics ( or more precisely a lens of the respective imaging optics).

The first imaging optics can be set up to form focal points of different wavelengths at different locations, the locations lying along a line segment that forms an acute angle to the optical axis of a lens of the first imaging optics.

According to a preferred embodiment of the invention, the light source comprises at least one pump source which emits pump light, the pump light being converted into polychromatic light by a plate-shaped luminophore.

A plate-shaped luminophore is understood here to be a luminophore that is expanded in two directions, but has only a slight expansion in the third direction. Light emerging through a side surface of the plate-shaped luminophore is advantageously used as measuring light. The side surface is a surface that is perpendicular to the base (the base is extended in two dimensions).

The luminophore is made of transparent material with a homogeneous refractive index, so that pump light and fluorescent light are transported in a straight line and without scattering by several millimeters. Single crystals doped with ions from the rare earth group, e.g. Ce: YAG, are suitable. However, transparent ceramics or glasses doped with photoluminescence centers can also be used.

Single crystals from Crytur are also suitable. These have a high index of refraction (1.82 at 532 nm) but are hard and difficult to machine. The typical plate thickness is 200 µm. For reasons of better producibility, it can be expedient to use a cover plate made of such a single crystal, which is bonded to a carrier plate and ground thin.

The use of a plate-shaped luminophore has the advantage that a largely homogeneous light distribution can be achieved in a simple manner for the light emerging from the side surface

The light from the pump source preferably enters through a side surface of the plate-shaped luminophore. Particularly preferably, the light enters through that side face which is opposite the side face through which the measurement light exits.

The typically blue (e.g. 450 nm) or violet (e.g. 405 nm) pump light is absorbed in the photoluminescence centers and re-emitted isotropically (i.e. uniformly in all directions) with a shifted wavelength. Because the generated polychromatic light is hardly scattered or absorbed (unless it is suitable for exciting fluorescence itself), its intensity can be accumulated.

For each point on the side surface of the luminophore through which the fluorescent light emerges from the luminophore, a capture area can be defined in the plate-shaped luminophore, i.e. a conical volume with a certain opening angle that has its tip in the point-shaped opening.

All light that arises in the capture area of the punctiform opening and runs to the point on the side surface can be used as measuring light. On the way there, the intensity portion of the light that can be coupled in increases continuously (accumulation).

If the measuring light is coupled into an optical fiber that is located behind the side surface, the opening angle of the cone is given by the maximum acceptance angle of the fiber. If, after exiting the luminophore, the measuring light is not transported via optical fibers but via free-beam optics, the opening angle is given by the aperture of the optics.

The polychromatic light that passes through the base surfaces and the side surfaces of the luminophore that are not used as light exit surfaces cannot be used as measuring light. In a preferred embodiment, the base surfaces and the side surfaces not used as a light exit surface are therefore made reflective.

Furthermore, polychromatic light that hits the side surface through which the measuring light exits at too great angles cannot be used as measuring light, since the point of origin is outside the capture range of the punctiform apertures.

In a preferred embodiment, the plate-shaped luminophore is therefore provided with a wedge angle between the two base surfaces, the wedge between the two base surfaces being designed so that the distance between the base surfaces at the location of the side surface through which the measuring light emerges is greater than that Distance at the location of that side surface through which the pump light enters. The wedge angle along the side surface at which the pump light penetrates is preferably between 1 ° and 10 °.

The wedge-shaped nature of the plate-shaped luminophore, possibly also with mirrored base surfaces, has the effect that the fluorescent light is guided towards the light exit surface at an increasingly flat angle after several reflections. In this way, a larger proportion of the fluorescent light can be used.

According to a further preferred embodiment, light from measuring light emerging from several side surfaces is used. For example, two fiber arrays can be attached to two side surfaces of the plate-shaped luminophore. The fiber ends of the individual fibers of the two fiber arrays facing away from the luminophore can be arranged in such a way that they form a line of punctiform openings and thus an elongated light exit surface. The optical fibers thus form a reshaping device which is set up to reshape a light distribution generated by the luminophore in such a way that the cross section of the light distribution becomes elongated.

When using plate-shaped luminophores, the reshaping device can have a plurality of fibers, the fibers each having a first fiber end, and wherein the first fiber ends receive polychromatic light that emerges from one or more side surfaces of the plate-shaped luminophore, as well as a second fiber end in each case, the second fibers are arranged in a line and form the light exit surface. The second fiber ends can serve as a confocal aperture at the same time.

In an alternative embodiment, the light from the pump source enters through a base area of the plate-shaped luminophore. This has the advantage that a larger area is available for coupling the pump light into the luminophore than with coupling in via a side surface.

As a result, a sufficiently large accumulated pump light power can also be achieved with pump light sources that have a comparatively low luminance when a large part of the base area is irradiated. In particular, LED arrays can be used as pump light sources, which represent an inexpensive alternative to laser diodes, for example.

LEDs emit light on a surface. They are easier to manufacture and have a higher electrical-optical efficiency than laser diodes. Because of their flat radiation, they are easier to cool than laser diodes. On the other hand, their luminance is much lower than that of laser diodes. Only the transparency of the luminophore and the accumulation effect make it possible to accumulate the luminance of all volume sections and bring it to a value sufficient for the measurement technology.

In a preferred embodiment, that base area which is opposite the light entry area of the pump light is made reflective. This has the advantage that pump light that hits this base area does not leave the luminophore, but can instead contribute to the generation of measurement light on the way back after reflection.

It is advantageous to make the plate-shaped luminophore thin, for example with a thickness of 50-200 μm, so that the thickness is comparable to the typical diameter of multimode fibers. As a result, a large part of the light that hits the side surface used as the light exit surface can be used as measuring light.

However, since the typical path length of the pump light in the Lumiphor is a few 100 µm, a large part of the pump light cannot contribute to the generation of fluorescent light despite the mirroring.

In an advantageous embodiment, the base area which is opposite the light entry area of the pump light is therefore provided with a surface-covering texture of pyramids. This texture prevents the pump light from traversing the plate vertically and on the shortest possible path. The pyramid texture does not have to be incorporated into the phosphor material; a textured top layer is sufficient.

According to a preferred embodiment, the light source comprises a slit diaphragm, the slit of the slit diaphragm being the light exit surface of the light source. The slot can simultaneously serve as the first confocal aperture of the measuring device.

The use of a reshaping device which is set up to reshape a light distribution generated by the luminophore in such a way that the cross section of the light distribution becomes more elongated has the general advantage that the light yield can be optimized. In the case of a rod-shaped and a plate-shaped luminophore, for example, only that part of the fluorescent light can be used as measurement light that hits the light exit surface below a certain critical angle (when using a fiber array, the critical angle is given, for example, by the maximum acceptance angle of the fibers).

Furthermore, the geometry of the rod-shaped or plate-shaped luminophore must be adapted to the geometry of the confocal aperture of the measuring device in order to enable the confocal aperture to be illuminated as homogeneously as possible.

These two restrictions can be circumvented by using a conversion device which receives an areal light distribution of the fluorescent light generated by the luminophore and converts it into an elongated light exit surface.

In a preferred embodiment, a planar arrangement of optical sub-elements is used as the reshaping device. The sub-elements can in particular be optical fibers or microlenses.

The arrangement of optical fibers can be such that the first fiber ends of each optical fiber are arranged on a surface and receive polychromatic light emitted by a luminophore and the respective second fiber ends of each optical fiber are arranged on a line and emit the polychromatic light. In this case, the arrangement of the second fiber ends forms the elongated light exit surface of the light source.

The arrangement of microlenses can be designed so that the microlenses are on a surface and split the polychromatic light into partial bundles, each partial bundle being passed on via further optical elements, for example deflection mirrors, and the individual light bundles being brought together to form an elongated light surface.

The planar arrangement of the optical sub-elements can in particular be optimized so that the largest possible proportion of the polychromatic light generated by the luminophore can be recorded and used as measuring light.

In a preferred embodiment, the light generated by the luminophore is collimated, and the planar arrangement of partial elements is attached to a circular surface within the collimated beam. In an alternative embodiment, the luminophore emits light in all spatial directions, and the planar arrangement of partial elements is arranged on a spherical surface or on part of a spherical surface around the luminophore.

One advantage of a light source using a conversion device that receives a planar distribution of polychromatic light and converts it into an elongated light distribution is that the geometry of the luminophore does not have to be adapted to the geometry of the (elongated) confocal aperture, but rather has to be designed in this way can that the highest possible light output results.

In a preferred embodiment, the luminophore has a frustoconical section, into the top surface of which the pump light is coupled, which generates polychromatic light in the luminophore. The outer surface of the luminophore is mirrored, so that the polychromatic light cannot leave the luminophore via the outer surface but is reflected on the outer surface.

Part of the polychromatic light that is generated in the luminophore hits the surface of the truncated cone. If the projection of a light beam points onto the symmetry axis of the truncated cone in the direction of the base, the angle between the light beam and the symmetry axis decreases after the reflection.

The polychromatic light finally passes through the base of the truncated cone at small angles to the axis of symmetry of the truncated cone and forms a circular planar light distribution.

The light is absorbed by a conversion device, for example a planar arrangement of fiber ends, and converted into an elongated light distribution.

In a further preferred embodiment, the luminophore has a cylindrical section, in the jacket surface of which there is an entry window for the pumped light. The pump light is radiated into the cylindrical luminophore through the entrance window in such a way that the pump light hits the inside of the cylinder jacket at a flat angle and experiences total reflection.

The cylindrical luminophore is designed in such a way that the pump light is forced onto a spiral path within the luminophore. The luminophore thus acts as a "trap" for the pump light, so that the pump light contributes completely to the generation of polychromatic light.

The polychromatic light leaves the luminophore through the outer surface and the base and is accordingly emitted in all spatial directions.

In order to collect and transmit the polychromatic light, a planar arrangement of fibers can be used, which are arranged on a surface around the luminophore. In particular, an arrangement of fibers can be used which are arranged on a spherical surface or a part of a spherical surface which surrounds the luminophore.

In an alternative embodiment, the luminophore has a frustoconical section, the entry window being located in the vicinity of the base and the pump light in the luminophore moving on a spiral path in the direction of the top surface. As a result of the inclination of the lateral surface, the pitch of the spiral path is successively reduced until the pump light finally runs back on a spiral path in the direction of the base area.

This embodiment has the advantage that the luminophore can be made more compact with the same yield due to the longer travel distance of the pump light.

The compactness can be further increased if the luminophore is designed in such a way that it consists of two truncated cones which are connected at the base, the entry window being located in the vicinity of one of the base surfaces. The light, which runs on a spiral path first in the direction of the top surface of one of the truncated cones and then back to the base, is guided on a spiral path to the second top surface and back to the base after passing through the base in the second truncated cone.

In another embodiment, the luminophore has a section which is in the shape of a preferably square truncated pyramid. The section is arranged relative to the pump source in such a way that the pump light enters the luminophore via the top surface of the truncated pyramid. Part of the polychromatic light that is generated in the luminophore hits the surface of the truncated pyramid. If the projection of a light beam points onto the symmetry axis of the truncated cone in the direction of the base, the angle between the light beam and the symmetry axis decreases after the reflection. The polychromatic light finally passes through its base at small angles to the axis of symmetry of the truncated pyramid and can therefore be more easily absorbed by a subsequent reshaping device, which converts the polygonal light distribution generated by the truncated pyramid into a linear light distribution.

A luminophore shaped in this way is easier and cheaper to manufacture than frustoconical luminophores and produces a more homogeneous intensity distribution.

So that neither the pump light nor the polychromatic light generated in the luminophore leave the truncated pyramid over its side surfaces, these should be mirrored.

A homogenizer can be arranged adjacent to the base of the truncated pyramid, which homogenizes the polychromatic light further, but no longer has to change the angular distribution. The homogenizer can, for example, be cuboid and adapted to the cross section of the luminophore.

The reshaping device can for example comprise a multiplicity of optical fibers, first ends of the optical fibers being distributed over an area and second ends of the optical fibers being distributed along a line. The first ends point to the luminophore or to the homogenizer, if one is provided.

Exemplary embodiments of the invention are explained in more detail below with reference to figures. The same reference symbols denote the same or corresponding elements. Show it:

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1

a schematic representation of a chromatic confocal measuring device;

Fig. 2

a first advantageous embodiment of the light source, in which several luminophores couple light into a homogenizer;

Fig. 3

a second advantageous embodiment of the light source, in which the luminophore is rod-shaped;

Fig. 4

a third advantageous embodiment of the light source, in which a rod-shaped luminophore illuminates a slit diaphragm;

Fig. 5

a fourth advantageous embodiment of the light source, in which the slit diaphragm is arranged inclined to the longitudinal axis of the luminophore;

Fig. 6

a fifth advantageous embodiment of the light source, in which the rod-shaped luminophore has a mirrored end face;

Fig. 7

a sixth advantageous embodiment of the light source, in which the luminophore is frustoconical;

Fig. 8

a seventh advantageous embodiment of the light source, in which a rod-shaped luminophore is surrounded by a parabolic groove for the purpose of collecting light;

Fig. 9

a schematic representation of an alternative chromatic-confocal measuring device, which additionally has a camera;

Figures 10a and 10b

schematic representations of a further alternative chromatic-confocal measuring device in a greatly simplified and a more detailed version, in which prisms generate a transverse chromatic focus shift;

Fig. 11

an eighth advantageous embodiment of the light source, in which the measuring light generated by the luminophore is focused on an elongated exit surface by a cylindrical lens;

Fig. 12

a further ninth advantageous embodiment of the light source, in which the pump light is focused on a rod-shaped luminophore through a cylindrical lens;

Fig. 13

a tenth advantageous embodiment of the light source, in which a homogenizer which is wedge-shaped in one direction is used;

Fig. 14

an eleventh advantageous embodiment of the light source, in which the luminophore is plate-shaped and the pump light is irradiated via a side surface;

Fig. 15

a twelfth advantageous embodiment of the light source, in which optical fibers receive the measuring light generated by a plate-shaped luminophore and transform it into a linear light distribution;

Fig. 16

a thirteenth advantageous embodiment of the light source, in which the luminophore is plate-shaped and the pump light is irradiated via one of the two base surfaces;

Fig. 17

a fourteenth advantageous embodiment of the light source in which the lumino-phore is frustoconical and the light is guided by total reflection inside the lumino-phore;

Fig. 18

a fifteenth advantageous embodiment of the light source, in which the lumino-phore is rod-shaped and the pump light is coupled into the luminophore via the curved cylinder surface;

Fig. 19

a sixteenth advantageous embodiment of the light source, in which the Lumi-nophor has the shape of a double truncated cone;

Fig. 20

a seventeenth advantageous embodiment of the light source, in which the lumino-phore has the shape of a square truncated pyramid;

Fig. 21

an eighteenth advantageous embodiment of the light source, in which the luminophore is rod-shaped and the polychromatic light emerging therefrom is passed through a homogenizer which has the shape of a square truncated pyramid.

DESCRIPTION OF PREFERRED EMBODIMENTS

Fig. 1 shows a schematic representation of a chromatic confocal measuring device. This comprises a light source 1 which emits polychromatic measurement light 2 through a light exit surface. The measuring light 2 passes through a first confocal diaphragm 3, which comprises a plurality of point-shaped openings or at least one slit-shaped opening and acts as a confocal aperture. The first confocal diaphragm 3 is imaged onto a measurement object 6 by means of imaging optics, which here include the lenses 4 and 5. At least one component of the imaging optics, here for example the lens 5, causes a chromatic focus shift, which leads to light of different wavelengths being imaged at different heights along the optical axis of the imaging optics.

Measurement light 2 is reflected by the measurement object and passes back through lens 5 into the imaging optics. According to the example, this includes a beam splitter 7 which directs part of the reflected measuring light 2 in the direction of a first receiving and evaluation unit 8. The measuring light 2 is imaged onto a second confocal diaphragm 10 through a further lens 9. According to the chromatic-confocal principle, only light of those wavelengths is sharply imaged on the second confocal diaphragm 10 that is also on the surface of the measurement object 6 were in focus. Light of these wavelengths passes through the second confocal diaphragm 10 with maximum intensity.

The first receiving and evaluation unit 8 measures the intensity of the measurement light reflected from the measurement object and passed through the second confocal diaphragm 10 as a function of the wavelength and the transverse position of the reflection point on the measurement object and uses this to determine the distances and / or thicknesses of several points or one in Area of the measurement object 6 extending at least in one spatial direction.

The Figures 2 to 8 , 11 and 12 show advantageous configurations of the light source 1.

Figure 2 shows a first advantageous embodiment of the light source 1. The light source 1 comprises, for example, a plurality of pump sources 20, for example laser diodes, which emit pump light 21 of a first wavelength. The pump light 21 is directed onto a plurality of luminophores 22 which convert the pump light 21 into polychromatic light 23 by a physical process, for example phosphorescence, fluorescence or scintillation. According to the example, the polychromatic light 23 comprises a spectrum of wavelengths, the wavelengths of the emission spectrum are typically greater than the wavelength of the pump light 21. The polychromatic light 23 can preferably also comprise part of the pump light 21 in addition to the emission spectrum.

In order to obtain an approximately uniform distribution of the emission intensity along the exit surface 24 of the light source 1, a homogenizer 25 is used. This preferably consists of a thin glass plate, which acts as an optical waveguide in one spatial direction. As a result, the polychromatic light 23 is advantageously guided in the direction of the exit surface 24 and is distributed almost uniformly along the extended dimension of the homogenizer 25. The light then emerges from the light exit surface 24 as a homogenized measuring light 26.

Figure 3 shows a second advantageous embodiment of the light source 1. The light source 1 according to the example comprises a pump source 30, for example a laser diode, which emits pump light 31 of a first wavelength. The pump light 31 is directed onto a rod-shaped luminophore 32, which by a physical process, for example Phosphorescence, fluorescence or scintillation, convert the pump light 31 into polychromatic light 33.

The pump light 31 preferably enters through a base area 34 of the rod-shaped luminophore 32. This has the advantage that the pump light passes through the entire length of the rod, so that as much pump light 31 as possible is converted.

The light 33 which emerges from a side surface of the rod-shaped luminophore 32 is used as the measuring light.

Due to the nature of the physical process (for example phosphorescence, fluorescence or scintillation), the light is generally not emitted uniformly along the length of the rod-shaped luminophore. This is in Figure 4 illustrated. Typically, most of the light 35 is emitted near the entrance surface, the emission decreasing exponentially over the length, as illustrated by the graph line 36. In addition, the emission is approximately homogeneous in all spatial directions and not only directed in the direction of the exit surface used. The view from the end face 37 shows the radial emission distribution. In order to ensure light exit only along the desired light exit surface, a slit diaphragm 38 is used, for example. The direction of the longer extension of the opening corresponds to the longitudinal direction of the rod-shaped luminophore 32.

Several advantageous possibilities are shown below for concentrating the light in the direction of the exit surface of the light source and for homogenizing it in the direction of the elongated extension. The individual measures can advantageously be combined with one another.

Figure 5 shows such an advantageous possibility. A slit diaphragm 58 is used here, which is tilted relative to the longitudinal axis of the rod-shaped luminophore 32. The slit diaphragm 58 is further away in the vicinity of the entry surface 34 of the luminophore 32 than in the vicinity of the opposite end face. As a result, a smaller proportion of the light emitted in the vicinity of the entrance surface 34 passes through the diaphragm, so that the higher emission is at least partially offset.

Figure 6 shows a further advantageous embodiment for homogenization. The end face 37 of the rod-shaped luminophore 32 opposite the entry face 34 is mirrored, so that pump light 31, which completely passes through the luminophore 32, is mirrored here and passes through again in the opposite direction. The emissions along the way there and back partially complement each other, so that the differences in intensity are partially offset.

Figure 7 shows a further advantageous embodiment for homogenization. Here the luminophore 72 is designed as a truncated cone. The end face 77 opposite the entry face 74 is smaller than the entry face 74. Since the luminophore functions as a waveguide for the pump light 31 due to its high refractive index, the pump light 31 is concentrated when it passes through the luminophore 72 due to the decreasing cross section. This increases the emission per unit volume along the route, which at least partially compensates for the decreasing emission. The reduction in the pumping light power along the route is answered by reducing the cross section, so that the pumping light intensity is kept at a uniform level.

Figure 8 shows a further advantageous embodiment of the light source 1 for homogenizing and concentrating the light. Here, the light source 1 comprises a parabolic mirror 89. The parabolic mirror is arranged such that at least part of the light which does not leave the rod-shaped luminophore 32 in the direction of the slit diaphragm 38 is reflected in the direction of the slit diaphragm. The parabolic mirror 89 is preferably a parabolic trough, that is to say a parabolic trough. In the section perpendicular to the channel axis, the concave borderline is a parabola. The channel axis is advantageously parallel to the axis of the luminophore 32.

In an advantageous variant, the cross section of the parabolic trough is changed over its length, in particular the trough has different depths at different points, for example deeper at one end than at the other or deeper in the middle than near the ends.

Figure 9 shows a schematic representation of an alternative chromatic-confocal measuring device. The measuring device essentially corresponds to that in Fig. 1 measuring device shown, except that a second beam splitter 97 between the first beam splitter 7 and the first receiving and evaluation unit 8 is arranged. This second beam splitter 97 directs part of the measurement light 2 reflected from the measurement object 6 onto a second receiving and evaluation unit 98.

For example, the second receiving and evaluation unit 98 is an imaging unit, preferably a camera.

The chromatic confocal measuring device of the Figures 10a and 10b includes like that of the Figure 1 a light source 1, a first confocal diaphragm 3 and imaging optics, consisting of lenses 4 and 5 and an additional optical element 101, here designed as a prime, through which the measuring light 2 is directed onto the measuring object 6. The confocal diaphragm 3 is designed here as a slit diaphragm, the direction of the slit being perpendicular to the plane of the drawing.

The axis of symmetry of the lens 5 is arranged at an angle to the average surface normal of the measurement object. The imaging optics are designed in such a way that, in addition to the chromatic aberration along the axis of the imaging optics, there is also a significant transverse chromatic focus shift. This is preferably provided by the additional optical element 101. Correspondingly, the measurement light 2 reflected by the measurement object 6 is captured at an angle by a second imaging optics, consisting of lenses 105 and 9, and an optical element 102. The second imaging optics are preferably designed to be mirror-symmetrical to the first imaging optics.

According to the embodiment of Figure 1 the measuring device comprises a second confocal aperture 10 and a first receiving and evaluation unit 8.

Figure 11 shows a further advantageous embodiment of the light source 1. The light source 1 according to the example comprises a pump source 120, for example a laser diode, which emits pump light 121 of a first wavelength. The pump light 121 is directed onto a luminophore 122, which converts the pump light 121 into polychromatic light 123 by a physical process, for example phosphorescence, fluorescence or scintillation. According to the example, the polychromatic light 123 comprises a spectrum of wavelengths, the wavelengths of this spectrum are typically greater than the wavelength of the pump light 121. The polychromatic light 123 can preferably also comprise part of the pump light 121.

In order to direct the light 123 onto an elongated exit surface, it is first collimated by means of a preferably aspherical lens 124 and then passes through a cylindrical lens 125, which focuses the light again on a line segment. A slit diaphragm 126 is preferably arranged at the location of the focal line, the slit opening of which represents the elongated exit surface of the light source 1.

Figure 12 shows a further advantageous embodiment of the light source 1. The light source 1 according to the example comprises a pump source 130, for example a laser, which emits pump light 131 of a first wavelength. The pump light 131 is first collimated by an aspherical lens 134 and then focused on a line segment by a cylindrical lens 135. A luminophore 136 is arranged at the location of the focus line and converts the pump light 131 into polychromatic light 137 by a physical process, for example phosphorescence, fluorescence or scintillation.

Figure 13 shows a further advantageous embodiment of the light source 1. The light source according to the example comprises a pump light source 210 which directs the pump light 211 onto a waveguide 212 which guides part of the pump light onto a wedge-shaped luminophore 215 so that the pump light hits the entire entrance surface of the luminophore.

The luminophore 215 converts the pump light into polychromatic light 213 and is designed in such a way that it acts as a waveguide for the polychromatic light. The luminophore is wedge-shaped in two spatial directions, the two spatial directions being orthogonal to the direction of propagation of the light. In the Figure 13 Examples of light rays are shown that show the geometric path of the polychromatic light.

The light which runs at large angles to the direction of propagation in the luminophore 215 hits one of the side surfaces. Due to the wedge-shaped shape of the waveguide, the light continues to travel at smaller angles to the direction of propagation after reflection. The Luminophore is designed such that the side length on the exit surface in one spatial direction corresponds to the desired side length of the light exit surface 214 in that spatial direction in which the light exit surface is only slightly extended.

The polychromatic light is propagated further in a second wedge-shaped waveguide 216, the second waveguide being wedge-shaped in only one spatial direction. The angle of the light to the direction of propagation is further flattened in one spatial direction by reflection on the side surfaces. The second waveguide is designed so that the side length on the light exit surface corresponds to that side length of the light exit surface in which the light exit surface is extended.

Due to the wedge-shaped shape of the waveguides, the polychromatic light leaves the light exit surface at a small opening angle, so that the finite aperture of the measuring device is sufficient to fully use the light as measuring light.

Figure 14 shows a further advantageous embodiment of the light source 1. The light source 1 according to the example comprises a pump source 150, for example a laser diode, which emits pump light 151 of a first wavelength. The pump light is directed onto a side surface of a plate-shaped luminophore 154.

For this purpose, the pump light is first collimated by collimation optics 152 and then focused by cylinder optics 153 in the direction in which the plate-shaped luminophore has a small extension. By focusing in one direction it is achieved that the distribution of the pump light on the entry surface is largely homogeneous and the largest possible part of the pump light generated by the pump light source can be coupled into the luminophore.

The luminophore converts pump light into polychromatic light 155. Part of the polychromatic light generated in the plate-shaped luminophore strikes the side surface opposite the entry surface of the pump light, possibly after reflection on one of the base surfaces or one of the side surfaces, and exits the luminophore through this side surface.

In order to increase the yield of measurement light, the base surfaces and those side surfaces that are not used as light exit surfaces can be made reflective.

Figure 15 shows a further advantageous embodiment of the light source 1. The light source here comprises a plurality of pump light sources 160, for example LEDs, which are positioned along a line and generate the pump light 161. The line of pump light sources is imaged by imaging optics 166 onto a side surface of a plate-shaped luminophore 164, which serves as an entry surface for the pump light

The line along which the pump light sources are arranged is parallel to that direction in which the entry surface is extended, so that a largely homogeneous illumination of the entry surface is achieved. The imaging optics are advantageously designed in such a way that the extension of the LEDs in the direction perpendicular to the line direction is comparable to the thickness of the plate-shaped luminophore.

In the case of LEDs with a width of 200 μm and a plate with a thickness of 200 μm, for example, a 1: 1 image is advantageous. The aperture of the imaging optics must be kept as large as possible so that as much pump light as possible can be coupled into the plate-shaped luminophore.

In an alternative embodiment, the linear arrangement of pump light sources can also be attached directly to the side surface of the plate-shaped luminophore, so that the pump light can be coupled into the plate-shaped luminophore without imaging optics.

In the Figure 15 The light source shown comprises a plurality of fibers 167, the fibers each having a first fiber end 168 which receives polychromatic light which is emitted by the luminophore through one of the side surfaces.

The fibers each have a second fiber end 169, the second fiber end emitting polychromatic light 165. The second fiber ends are arranged in a line and form a light exit surface.

By capturing polychromatic light that leaves the Lumiophor through more than one side surface, the yield is increased.

Figure 16 shows a further advantageous embodiment of the light source 1. The light source 1 according to the example comprises a planar pump light source 170, which is designed here as an array of LEDs extended in two spatial directions.

The pump light 171 generated by the pump light source enters through a first base surface of the plate-shaped luminophore 174 and generates polychromatic light 175 which leaves the luminophore through one of the side surfaces. The second base area of the luminophore can be made reflective so that the pump light can also contribute to the generation of polychromatic light after reflection on the second base area.

Figure 17 shows a further advantageous embodiment of the light source 1. The light source according to the example comprises a pump source 180, for example a laser diode, which emits pump light 181 of a first wavelength. The pump light is directed through imaging optics 182 onto the top surface of a luminophore 183 which has the shape of a truncated cone.

The light source comprises a multiplicity of optical fibers 184, each having a first fiber end 185, the first fiber ends being positioned in a planar arrangement near the base of the luminophore and receiving the polychromatic light generated by the luminophore, as well as a second fiber end 186 each, wherein the second fiber ends are arranged in a line, emit the polychromatic light 187 and together form the light exit surface of the light source.

In order to minimize the portion of the light that hits the first fiber ends at too steep an angle and thus cannot be coupled into the fibers, the luminophore is designed in the form of a truncated cone.

In the Figure 17 Examples of light rays are shown that demonstrate the geometric path of fluorescent light that was generated by the luminophore and that has a large angle to the axis of symmetry of the truncated cone. Successive reflections on the inside of the lateral surface of the truncated cone create the angle between the light rays and the axis of symmetry of the truncated cone is reduced further and further, in particular to the extent that the light can be coupled into the fiber ends.

The planar arrangement of the fiber ends can in particular be designed in such a way that the part of the base area that is penetrated by the polychromatic light is covered as completely as possible, so that the largest possible part of the light can be coupled into the fibers and carried on.

Figure 18 shows a further advantageous embodiment of the light source 1. The light source according to the example comprises a pump source 190, for example a laser diode, which emits pump light 191 of a first wavelength. The light source further comprises a cylindrical luminophore 193.

The cylindrical luminophore is provided with an entry window 198 through which the pump light is coupled into the luminophore. If the pump light is focused at the level of the entry window, the size of the entry window can be kept very small. For example, an extension of 10 μm for the entry window can be sufficient.

The pump light is coupled in such that the pump light hits the inside of the lateral surface at a flat angle and experiences total reflection. This behavior is repeated in the case of successive reflections on the inside of the lateral surface, so that the pump light is forced onto a spiral path within the cylindrical luminophore.

Advantageously, the cylindrical luminophore is designed in such a way that the pump light on its way along the spiral path from the entrance window to the base of the cylinder largely contributes to the generation of polychromatic light. With a typical mean free path of the pump light in the luminophore of 200 μm, this is ensured, for example, with a path length of 1 mm.

The cylindrical luminophore can be implemented very compactly and at the same time provide a sufficiently large path length for the pump light. For example, the cylinder can have a radius of 25 µm and the pitch of the spiral path 20 µm (whereby with an entrance window of 10 µm it is ensured that the pump light does not leave the cylindrical luminophore again through the entrance window after the first circling).

With a height of 150 µm of the cylinder it is achieved that the pump light can cover 6 circles and thus a path length of more than 1mm on the way from the entrance window to the base area.

The polychromatic light 197 is emitted by the luminophore over the lateral surface and the base surfaces in all spatial directions. The light source comprises a plurality of fibers, each of which has first fiber ends 195 which are arranged on a surface that partially encloses the luminophore. The fiber ends are preferably packed as tightly as possible in order to collect and transmit the largest possible part of the polychromatic light.

The respective second fiber ends of the fibers are arranged in a line and form an elongated light exit surface.

Figure 19 shows a further advantageous embodiment of the light source 1. The light source according to the example comprises a luminophore 203, which is designed in the form of two truncated cones, which are connected at the base. The pump light 201 is coupled into the luminophore through an entry window 208, the pump light in the luminophore being forced onto a spiral path by successive total reflections and generating polychromatic light 207.

Due to the opening angle of the truncated cone, the path height of the pumping light on the way in the first truncated cone from the entrance window to the first top surface decreases until the pumping light moves back to the base surface. The pump light can continue in the second truncated cone, where the behavior is repeated.

This configuration of the luminophore allows long path lengths of the pump light in the luminophore to be achieved with a very compact design. This also enables the use of photoluminescent materials whose half-value length is greater than 1 mm is, for example, very transparent phosphor-in-glass materials, which are advantageous compared to single crystals because of their heat resistance, easier processing and the generation of broadband and evenly bright spectra.

Figure 20 shows a further advantageous embodiment of the light source 1, which is essentially that in FIG Figure 17 corresponds to the light source shown. The light source according to the example comprises a pump source 310, for example a laser diode, which emits pump light 311 of a first wavelength. The pump light 311 is directed through an imaging optics 312 onto a luminophore 313 which, in this exemplary embodiment, has the shape of a square truncated pyramid, over the top surface of which the pump light 311 is coupled. The cross section of the luminophore 313 is thus square and increases continuously with increasing distance from the top surface to the base of the truncated pyramid. The side surfaces of the truncated pyramid are mirrored so that no light can escape through the side surfaces.

In this exemplary embodiment, the base area adjoins a square side surface of a cuboid made of glass, which forms a homogenizer 314. If the luminophore 313 is of sufficient length, the homogenizer 314 can be omitted.

The light source 1 also comprises a shaping device which is formed by a plurality of optical fibers 315. First fiber ends of the fibers 315 are arranged flat in the vicinity of the other square side surface of the homogenizer 314 and receive the polychromatic light generated by the luminophore and transmitted by the homogenizer 314. The second fiber ends of the optical fibers 315 are arranged along a line and together define the linear exit surface 316 of the light source 1.

The truncated pyramid-shaped luminophore 313 minimizes the portion of the light which strikes the first fiber ends of the optical fibers 315 at an angle that is too steep and thus cannot be coupled into the fibers 315. Compared to the conical shape of the luminophore, as shown in the Figure 17 shown, the pyramidal shape has the advantage that it can be made more easily from the often difficult to machine luminophoric materials. In addition, it has surprisingly been shown that the pyramidal shape to a leads to a more uniform intensity distribution on the base of the luminophore. In the case of rotationally symmetrical luminophores, an undesirable concentration of the polychromatic light on the axis of symmetry is usually observed.

In the Figure 20 light rays are indicated with dashed lines which demonstrate the geometric path of fluorescent light which was generated by the luminophore 313 and which initially has a large angle to the axis of symmetry of the truncated pyramid. Through successive reflections on the inside of the lateral surface of the truncated pyramid, the angle between the light rays and the axis of symmetry of the truncated cone is reduced until the light can be coupled into the ends of the optical fibers 315 with little loss.

In contrast to what is shown for reasons of clarity, the planar arrangement of the fiber ends can in particular be designed in such a way that the part of the base area of the homogenizer 314 (or, in the absence of the latter, the luminophore 313) through which the polychromatic light passes is covered as completely as possible that the largest possible part of the light can be coupled into the fibers 315 and passed on.

Figure 21 shows a further advantageous embodiment of the light source 1, the elements from the Figures 13 , 17th and 20th shown embodiments combined.

The light source according to the example comprises a pump source 320, for example a laser diode, which emits pump light 321 of a first wavelength. The pump light 321 is directed onto the end face of a rod-shaped luminophore 323 by means of imaging optics 322. In this embodiment the rod has a circular cross-section. However, oval, square, rectangular or other regular or irregular polygonal cross-sections are also possible. The side surfaces of the luminophore 323 are mirrored so that no light can escape to the outside via the side surfaces.

In this exemplary embodiment, the other end face of the rod-shaped luminophore 323 adjoins a square top surface of a homogenizer 324 which is made of glass and has the shape of a truncated pyramid. The cross section of the homogenizer is square and increases continuously with increasing distance from the luminophore 323 to the base of the truncated pyramid.

The light source 1 also includes a reshaping device, which is also formed here by a multiplicity of optical fibers 325. First ends of the fibers 325 are arranged flat in the vicinity of the square base of the homogenizer 324 and absorb the polychromatic light generated by the luminophore and transmitted by the homogenizer 324. The second ends of the optical fibers 325 are arranged along a line and together define the linear exit surface 326 of the light source 1.

The homogenizer 324 minimizes the portion of the light which strikes the first ends of the optical fibers 325 at an angle that is too steep and therefore cannot be coupled into the fibers 325.

Compared to the embodiment according to Figure 20 has the in the Figure 21 The light source 1 shown has the advantage that the geometry of the luminophore 323 can be determined primarily from the point of view of ease of manufacture. The more complicated, but very advantageous geometry of the pyramidal homogenizer 324 with regard to the homogenization and the coupling into the fiber ends, on the other hand, can easily be realized from the material glass. The conversion of the polychromatic light into the linear exit surface 326 is also undertaken in this exemplary embodiment by the conversion device formed by the optical fibers 325.

1. 1. Chromatisch-konfokale Messvorrichtung zur Messung von Abständen und/oder Dicken von mehreren Stellen simultan oder eines in mindestens eine Raumrichtung ausgedehnten Bereichs eines Messobjekts, umfassend
   eine Lichtquelle (1), welche durch eine Lichtaustrittsfläche polychromatisches Messlicht (2) emittiert,
   mindestens eine erste konfokale Apertur (3, 10), durch die das Messlicht (2) tritt, wobei die erste konfokale Apertur (3, 10) eine Mehrzahl von punktförmigen Öffnungen oder mindestens eine schlitzförmige Öffnung umfasst,
   eine Abbildungsoptik (4, 5, 101), welche dazu eingerichtet ist, eine chromatische Fokusverschiebung des Messlichts hervorzurufen und die erste konfokale Apertur (3) in ein Messvolumen abzubilden, wobei verschiedene Wellenlängen in verschiedenen Höhen fokussiert sind,
   eine erste Empfangs- und Auswerteeinheit (8), welche ausgebildet ist, um die Intensität des vom Messobjekt reflektierten Messlichts in Abhängigkeit der Wellenlänge und der transversalen Position der Reflexionsstelle auf dem Messobjekt zu messen und daraus Abstände und/oder Dicken von mehreren Stellen oder eines in mindestens eine Raumrichtung ausgedehnten Bereichs des Messobjekts (6) zu bestimmen,
   dadurch gekennzeichnet, dass
   die Lichtquelle (1) eine lasergepumpte Luminophor-basierte Lichtquelle ist und die Austrittsfläche (24) länglich ist.
2. 2. Messvorrichtung nach Satz 1, dadurch gekennzeichnet, dass die Lichtquelle (1) mindestens eine Pumpquelle (20) umfasst, welche Pumplicht (21) emittiert und auf einen Luminophor richtet, der das Pumplicht (21) in polychromatisches Licht (23) umwandelt.
3. 3. Messvorrichtung nach Satz 2, dadurch gekennzeichnet, dass das polychromatische Licht (23) anschließend durch einen Homogenisator (25) tritt, derart, dass die Intensität des von der Austrittsfläche (24) austretenden Lichts (26) zumindest nahezu gleichmäßig verteilt ist.
4. 4. Messvorrichtung nach Satz 2 oder 3, dadurch gekennzeichnet, dass der Luminophor (32) stabförmig ist, wobei durch eine Seitenfläche des stabförmigen Luminophors (32) austretendes Licht (33) als Messlicht verwendet wird.
5. 5. Messvorrichtung nach Satz 4, dadurch gekennzeichnet, dass die Lichtquelle (1) eine Schlitzblende (38) umfasst, wobei der Schlitz der Schlitzblende (38) die Lichtaustrittsfläche der Lichtquelle (1) ist.
6. 6. Messvorrichtung nach Satz 5, dadurch gekennzeichnet, dass die Schlitzblende (58) relativ zur Längsachse des stabförmigen Luminophors (32) verkippt ist.
7. 7. Messvorrichtung nach einem der Sätze 4 bis 6, dadurch gekennzeichnet, dass die einer Eintrittsfläche (34), durch welche das Pumplicht (31) in den Luminophor (32) eintritt, gegenüberliegende Stirnfläche (37) des stabförmigen Luminophors (32) verspiegelt ausgeführt ist.
8. 8. Messvorrichtung nach einem der Sätze 4 bis 7, dadurch gekennzeichnet, dass die Lichtquelle (1) einen Parabolspiegel (89) umfasst.
9. 9. Messvorrichtung nach Satz 2 oder 3, dadurch gekennzeichnet, dass der Luminophor plattenförmig ist.
10. 10. Messvorrichtung nach Satz 9, dadurch gekennzeichnet, dass der Luminophor so angeordnet ist, dass das Pumplicht durch eine Seitenfläche in den Luminophor eindringt und das Messlicht auf einer gegenüberliegenden Seitenfläche aus dem Luminophor austritt.
11. 11. Messvorrichtung nach Satz 10, dadurch gekennzeichnet, dass Grundflächen des Luminophors entlang einer Seitenfläche, die senkrecht zu derjenigen Seitenfläche steht, an der das Pumplicht eindringt, einen Keilwinkel zwischen 1° und 10° einschließen.
12. 12. Messvorrichtung nach Satz 9, dadurch gekennzeichnet, dass der Luminophor so angeordnet ist, dass das Pumplicht durch eine der beiden Grundflächen des Luminophors eindringt und das Messlicht aus einer senkrecht zur der Grundfläche angeordneten Seitenfläche des Luminophors austritt.
13. 13. Messvorrichtung nach einem der vorhergehenden Sätze, dadurch gekennzeichnet, dass die Lichtquelle eine Umformungseinrichtung aufweist, die dazu eingerichtet ist, eine Lichtverteilung so umzuformen, dass der Querschnitt der Lichtverteilung länglicher wird.
14. 14. Messvorrichtung nach Satz 13, dadurch gekennzeichnet, dass die Umformungseinrichtung eine Anordnung von Lichtleitfasern umfasst.
15. 15. Messvorrichtung nach einem der Sätze 2 oder 3, dadurch gekennzeichnet, dass der Luminophor einen kegelstumpfförmigen Abschnitt hat.
16. 16. Messvorrichtung nach Satz 14, dadurch gekennzeichnet, dass der Abschnitt eine gekrümmte Außenfläche hat, die verspiegelt ist, und dass der Abschnitt so angeordnet ist, dass das Pumplicht über die Deckfläche des Kegelstumpfes in den Luminophor eintritt.
17. 17. Messvorrichtung nach einem der Sätze 2 oder 3, dadurch gekennzeichnet, dass der Luminophor einen zylindrischen Abschnitt hat, der so angeordnet ist, dass über die zylindrische Außenfläche eingekoppeltes Pumplicht durch Totalreflexion in dem Abschnitt gehalten wird.
18. 18. Messvorrichtung nach einem der Sätze 2 oder 3, dadurch gekennzeichnet, dass der Luminophor (213) einen Abschnitt hat, der die Form eines vorzugsweise quadratischen Pyramidenstumpfes hat, der so angeordnet ist, dass das Pumplicht über die Deckfläche des Pyramidenstumpfes in den Luminophor (213) eintritt.
19. 19. Messvorrichtung nach Satz 18, dadurch gekennzeichnet, dass Seitenflächen des Pyramidenstumpfes verspiegelt sind.
20. 20. Messvorrichtung nach Satz 18 oder 19, dadurch gekennzeichnet, dass benachbart zu der Grundfläche des Pyramidenstumpfes ein Homogenisator (225) angeordnet ist.
21. 21. Messvorrichtung nach Satz 20, dadurch gekennzeichnet, dass der Homogenisator (225) quaderförmig ist.
22. 22. Messvorrichtung nach einem der Sätze 18 bis 21, gekennzeichnet durch eine Umformungseinrichtung, die eine Vielzahl optischer Fasern (214) umfasst, wobei erste Enden der optischen Fasern (214) über eine Fläche verteilt und zweite Enden der optischen Fasern entlang einer Linie verteilt angeordnet sind.
23. 23. Messvorrichtung nach einem der vorangegangenen Sätze, dadurch gekennzeichnet, dass die Messvorrichtung eine zweite Empfangs- und Auswerteeinheit (98) umfasst, welche ausgebildet ist, um eine Abbildung des Messobjekts (6) zu erfassen.
24. 24. Messvorrichtung nach einem der vorangegangenen Sätze, dadurch gekennzeichnet, dass die Messvorrichtung eine zweite Abbildungsoptik (105, 102, 9) umfasst, welche räumlich getrennt von der ersten Abbildungsoptik (4, 101, 5) ausgeführt ist, wobei die erste Abbildungsoptik und die zweite Abbildungsoptik je ein zusätzliches optisches Element (101, 102) umfassen, welches eine chromatische Fokusverschiebung quer zur optischen Achse einer Linse (5, 105) der jeweiligen Abbildungsoptik verursacht.
25. 25. Messvorrichtung nach Satz 24, dadurch gekennzeichnet, dass die erste Abbildungsoptik dazu eingerichtet ist, Fokuspunkte unterschiedlicher Wellenlängen an unterschiedlichen Orten zu bilden, wobei die Orte entlang eines Liniensegments liegen, das einen spitzen Winkel zur optischen Achse einer Linse (5) der ersten Abbildungsoptik (4, 101, 5) bildet.

Important aspects of the present invention are summarized in the following sentences:

1. 1. Chromatic-confocal measuring device for measuring distances and / or thicknesses of several points simultaneously or an area of a measuring object that is extended in at least one spatial direction
   a light source (1) which emits polychromatic measuring light (2) through a light exit surface,
   at least one first confocal aperture (3, 10) through which the measuring light (2) passes, the first confocal aperture (3, 10) comprising a plurality of point-shaped openings or at least one slot-shaped opening,
   an imaging optics (4, 5, 101) which are set up to cause a chromatic focus shift of the measurement light and to image the first confocal aperture (3) in a measurement volume, with different wavelengths being focused at different heights,
   a first receiving and evaluation unit (8), which is designed to measure the intensity of the measurement light reflected from the measurement object as a function of the wavelength and the transverse position of the reflection point on the measurement object and to measure the distances and / or thicknesses of several points or one in to determine at least one area of the measurement object (6) extending over one spatial direction,
   characterized in that
   the light source (1) is a laser-pumped luminophore-based light source and the exit surface (24) is elongated.
2. 2. Measuring device according to sentence 1, characterized in that the light source (1) comprises at least one pump source (20) which emits pump light (21) and directs it onto a luminophore which converts the pump light (21) into polychromatic light (23).
3. 3. Measuring device according to sentence 2, characterized in that the polychromatic light (23) then passes through a homogenizer (25) such that the intensity of the light (26) emerging from the exit surface (24) is at least almost uniformly distributed.
4. 4. Measuring device according to sentence 2 or 3, characterized in that the luminophore (32) is rod-shaped, light (33) emerging through a side surface of the rod-shaped luminophore (32) being used as measuring light.
5. 5. Measuring device according to sentence 4, characterized in that the light source (1) comprises a slit diaphragm (38), the slot of the slit diaphragm (38) being the light exit surface of the light source (1).
6. 6. Measuring device according to sentence 5, characterized in that the slit diaphragm (58) is tilted relative to the longitudinal axis of the rod-shaped luminophore (32).
7. 7. Measuring device according to one of sentences 4 to 6, characterized in that the one entry surface (34) through which the pump light (31) enters the luminophore (32), the opposite end face (37) of the rod-shaped luminophore (32) is mirrored is.
8. 8. Measuring device according to one of sentences 4 to 7, characterized in that the light source (1) comprises a parabolic mirror (89).
9. 9. Measuring device according to sentence 2 or 3, characterized in that the luminophore is plate-shaped.
10. 10. Measuring device according to sentence 9, characterized in that the luminophore is arranged so that the pump light penetrates through a side surface into the luminophore and the measurement light exits the luminophore on an opposite side surface.
11. 11. Measuring device according to sentence 10, characterized in that the base surfaces of the luminophore enclose a wedge angle between 1 ° and 10 ° along a side surface which is perpendicular to the side surface on which the pump light penetrates.
12. 12. Measuring device according to sentence 9, characterized in that the luminophore is arranged such that the pump light penetrates through one of the two base surfaces of the luminophore and the measuring light exits from a side surface of the luminophore arranged perpendicular to the base surface.
13. 13. Measuring device according to one of the preceding sentences, characterized in that the light source has a conversion device which is set up to to reshape a light distribution so that the cross-section of the light distribution becomes elongated.
14. 14. Measuring device according to sentence 13, characterized in that the shaping device comprises an arrangement of optical fibers.
15. 15. Measuring device according to one of sentences 2 or 3, characterized in that the luminophore has a frustoconical section.
16. 16. Measuring device according to sentence 14, characterized in that the section has a curved outer surface which is mirrored, and that the section is arranged such that the pump light enters the luminophore via the top surface of the truncated cone.
17. 17. Measuring device according to one of sentences 2 or 3, characterized in that the luminophore has a cylindrical section which is arranged in such a way that pump light coupled in via the cylindrical outer surface is held in the section by total reflection.
18. 18. Measuring device according to one of sentences 2 or 3, characterized in that the luminophore (213) has a section which has the shape of a preferably square truncated pyramid, which is arranged so that the pump light over the top surface of the truncated pyramid into the luminophore ( 213) occurs.
19. 19. Measuring device according to sentence 18, characterized in that the side surfaces of the truncated pyramid are mirrored.
20. 20. Measuring device according to sentence 18 or 19, characterized in that a homogenizer (225) is arranged adjacent to the base of the truncated pyramid.
21. 21. Measuring device according to sentence 20, characterized in that the homogenizer (225) is cuboid.
22. 22. Measuring device according to one of sentences 18 to 21, characterized by a conversion device which comprises a plurality of optical fibers (214), wherein first ends of the optical fibers (214) distributed over an area and second ends of the optical fibers are arranged distributed along a line.
23. 23. Measuring device according to one of the preceding sentences, characterized in that the measuring device comprises a second receiving and evaluation unit (98) which is designed to detect an image of the measurement object (6).
24. 24. Measuring device according to one of the preceding sentences, characterized in that the measuring device comprises a second imaging optics (105, 102, 9) which are spatially separated from the first imaging optics (4, 101, 5), wherein the first imaging optics and the second imaging optics each comprise an additional optical element (101, 102) which causes a chromatic focus shift transversely to the optical axis of a lens (5, 105) of the respective imaging optics.
25. 25. Measuring device according to sentence 24, characterized in that the first imaging optics are set up to form focal points of different wavelengths at different locations, the locations lying along a line segment that forms an acute angle to the optical axis of a lens (5) of the first imaging optics (4, 101, 5).

Claims (17)

Chromatic-confocal measuring device for measuring distances and / or thicknesses of several points simultaneously or comprising an area of a measuring object that is extended in at least one spatial direction
a light source (1) which emits polychromatic measuring light (2) through a light exit surface,
at least one first confocal aperture (3, 10) through which the measuring light (2) passes, the first confocal aperture (3, 10) comprising a plurality of point-shaped openings or at least one slot-shaped opening,
an imaging optics (4, 5, 101) which are set up to cause a chromatic focus shift of the measurement light and to image the first confocal aperture (3) in a measurement volume, with different wavelengths being focused at different heights,
a first receiving and evaluation unit (8), which is designed to measure the intensity of the measurement light reflected from the measurement object as a function of the wavelength and the transverse position of the reflection point on the measurement object and to measure the distances and / or thicknesses of several points or one in to determine at least one area of the measurement object (6) extending over one spatial direction,
characterized in that
the light source (1) is a laser-pumped luminophore-based light source and the exit surface (24) is elongated. Measuring device according to claim 1, characterized in that the light source (1) comprises at least one pump source (20) which emits pump light (21) and directs it onto a luminophore which converts the pump light (21) into polychromatic light (23). Measuring device according to claim 2, characterized in that the polychromatic light (23) then passes through a homogenizer (25; 324) in such a way that the intensity of the light (26) emerging from the exit surface (24) is at least almost uniformly distributed. Measuring device according to claim 3, characterized in that the homogenizer (225) has a section which is in the form of a truncated pyramid which is arranged such that the polychromatic light enters the section via the top surface of the truncated pyramid. Measuring device according to claim 4, characterized in that side surfaces of the truncated pyramid are inclined in such a way that polychromatic light guided in the section is guided by total reflection in the homogenizer (225). Measuring device according to claim 2, characterized in that the pump light (31) is converted by a rod-shaped luminophore (32) into polychromatic light (33), light (33) emerging through a side surface of the rod-shaped luminophore (32) being used as measuring light. Measuring device according to one of Claims 2 to 5, characterized in that the luminophore (174) is plate-shaped. Measuring device according to one of Claims 2 to 5, characterized in that the luminophore (183) has a frustoconical section. Measuring device according to Claim 8, characterized in that the section has a curved outer surface which is mirrored, and in that the section is arranged such that the pump light enters the luminophore (183) via the top surface of the truncated cone. Measuring device according to one of Claims 2 to 5, characterized in that the luminophore (313) has a section which has the shape of a truncated pyramid which is arranged such that the pump light enters the section via the top surface of the truncated pyramid. Measuring device according to claim 10, characterized in that side surfaces of the truncated pyramid are mirrored. Measuring device according to claim 10 or 11, characterized in that a homogenizer (314) is arranged adjacent to the base of the truncated pyramid. Measuring device according to one of the preceding claims, characterized in that the light source has a reshaping device which is set up to reshape a light distribution in such a way that the cross section of the light distribution becomes more elongated. Measuring device according to Claim 13, characterized in that the shaping device comprises an arrangement of optical fibers (224; 315). Measuring device according to one of the preceding claims, characterized in that the measuring device comprises a second receiving and evaluation unit (98) which is designed to detect an image of the measurement object (6). Measuring device according to one of the preceding claims, characterized in that the measuring device comprises a second imaging optics (105, 102, 9) which are spatially separated from the first imaging optics (4, 101, 5), the first imaging optics and the second imaging optics each comprise an additional optical element (101, 102) which causes a chromatic focus shift transverse to the optical axis of a lens (5, 105) of the respective imaging optics. Measuring device according to claim 16, characterized in that the first imaging optics are set up to form focal points of different wavelengths at different locations, the locations lying along a line segment that forms an acute angle to the optical axis of a lens (5) of the first imaging optics (4 , 101, 5).

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